You are probably very glad you didn't buy that house.

While the total volume of the water in my basement never reached yours, I had a slightly similar problem the first spring, and this last one. Since I'm on top of a hill, the water table wasn't involved, just the way rain hits the southwest side of the house and seeps in through one or more cracks where the cement wall of the basement connects to the cement floor. I'm told those cracks are difficult to avoid in construction and almost impossible to mend afterwards. ARGGG

An engineer friend suggested I dig the soil and gravel away from the back wall outside, lay down heavy plastic, and replace the soil/gravel so it would have a better drain tilt away from the wall. So, last summer that's what we did when the new deck was built out there. I await the rain to find out if it's going to work, of course.

So far we've had an unusual amount of snow here, and it has melted several times with all the snow and slush from the roof falling right into the "zone" where the plastic was laid. No sign of water in the basement yet... but the spring rains are still to come, and that will be the acid test.

We shall see.